This invention relates to a stud finder.
A stud finder typically employs a magnetic element which senses the presence of a ferrous metal object, such as the head of a nail or screw, in a wall. The presence of a nail or screw typically indicates the location of a stud in the wall. Stud finders of this type are shown in U.S. Pat. Nos. 3,845,384, 2,933,679 and 4,896,131.
Stud finders typically include a marking groove or notch at one or more of its outer edges, so that the user can mark the wall after the location of the stud has been determined. This type of arrangement does not provide a great deal of accuracy in marking the wall at a point corresponding to the location of the head of the nail or screw.
It is an object of the present invention to provide a stud finder which allows a user to accurately mark the wall in a location corresponding to the location of the head of the nail or screw. It is a further object of the invention to provide a stud finder with a level indicating feature to assist in accurately marking the location of the stud, in which the level indicating feature is inexpensive in construction and does not significantly add to the cost of manufacture of the stud finder.
In accordance with one aspect of the invention, a stud finder includes a base member, and a magnetic subassembly mounted to the base member which detects the presence of a ferrous metal object in a wall when the base member is positioned thereagainst. A level indicator is mounted to the base member, for indicating the position of the base member relative to vertical when the presence of a nail or screw head is detected by the magnetic subassembly. A vertical slot is formed in the base member, and defines a linear marking edge. When the location of a stud is determined by use of the magnetic subassembly, the base member is moved on the wall until the level indicator reads level. The marking edge is thus positioned vertically, and is employed by the user to make a mark on the wall. In a preferred embodiment, the location of the marking edge is such that it is in vertical alignment with the magnetic subassembly. Accordingly, when the magnetic subassembly detects the presence of a nail or screw head and the base member is moved so as to indicate level on the level indicator, the marking edge is vertically aligned with the nail or screw head, and the mark made by the user is in vertical alignment with the nail or screw head. In this manner, the location of the stud within the wall can be accurately marked by the user.
The level indicator preferably comprises a level vial mounted to the base member so as to be clearly visible by the user when a rear surface of the base member is placed against the wall. The level vial is oriented such that its longitudinal axis is perpendicular to the linear marking edge defined by the slot formed in the base member. In a preferred form, the magnetic subassembly is mounted at one end of the base member and the level vial at the other, with the slot located between the magnetic subassembly and the level vial.
The invention also contemplates a method of marking the location of a stud in a wall, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.